The Automated Quantitative Microscopy System (AQMS) is a new shared facility that will consist of a research microscope with stage drivers and position sensors, a Camera Lucida, Color Video Camera, a Scanning Microdensitometer, a Minicomputer and Image Display System, and a Printer Plotter. It will be used by scientists from several departments of the University of Washington, all of whom will use the system for projects currently funded by the NIH. All are core staff members or affiliates of the Regional Primate Research Center where the AQMS would be located. No instrumentation comparable in terms of speed and flexibility exists at the University of Washington or neighboring institutions. The AQMS will be used to gather dimensional data from microscope slides and density data from autoradiographic films. It will provide information about the perimeters, surface areas and volumes of neuroanatomical structures; it will record the locations of labeled cells within the brain or other structures, and compare their optical density with that of adjacent cells; it will provide a means for semiautomatic cell counting of neural and other cells, tracing of neural pathways, evaluating metabolic activity levels in localized brain areas by the 2-deoxyglucose method, and generate three-dimensional color-coded images of all of the above. A major user group of eight Core Staff scientists and Research Affiliate scientists of the Center will use the AQMS for research on Auditory Perception, Visual Development and Deprivation, Oculomotor System Studies, Neural Control of Circulation, Effects of Intracerebral Drug Injections and Developmental Physiology. All of the studies, which are summarized in Table I, focus on brain mechanisms of the functions of interest. They will require 90% of the usage of the instrumentation. The Primate Center's Bioengineering Division will exercise responsibility for assembling, programming, and maintaining the apparatus. An AQMS Advisory Committee with representatives from several University departments and the major computing centers will advise on policies to maximize utilization of the facility. A Core Staff scientist of the Primate Center will supervise day-to-day operations.